When an object is subjected to an impact force, a stress wave is transmitted through the object. This stress wave causes deformations in the internal structure of the object. As the object deforms it acts, in part, as a shock absorber, dissipating a portion of the mechanical energy associated with the impact. The ability of the object to dissipate mechanical energy, commonly referred to as the “damping capacity” of the object, depends on several factors, including the type and structural integrity of the materials comprising the object.
Instruments have been developed that are capable of quantitatively measuring the damping capacity of an object. An example of such an instrument is described in U.S. Pat. No. 6,120,466 (“the '466 patent”), issued 19 Sep. 2000 and entitled “System and Method for Quantitative Measurements of Energy Damping Capacity,” the entire disclosure of which is hereby incorporated by reference herein. The instrument disclosed in the '466 patent provides an objective, quantitative measurement of the damping capacity of an object, referred to as the loss coefficient η. The energy of an elastic wave attenuates relatively quickly in materials with a relatively high loss coefficient, whereas the energy of an elastic wave attenuates relatively slowly in materials with a relatively low loss coefficient.
The damping capacity of an object is an important parameter in a wide variety of applications. For example, in the field of dentistry, when a healthy tooth is subjected to an impact force, the mechanical energy associated with the impact is primarily dissipated by the periodontal ligament. Changes in the structure of the periodontal ligament that reduce its ability to dissipate the mechanical energy associated with an impact force, and thus reduce overall tooth stability, can be detected by measuring the loss coefficient of the tooth.